.block-div {
    background-color: aqua;
    width: 600px;
    height: 100px;
}

#block-div-1 {
    background-color: bisque;
}

#block-div-2 {
    background-color: chartreuse;
}
.inline-div {
    display: inline
}

#inline-div-1 {
    background-color: bisque;
}

#inline-div-2 {
    background-color: chartreuse;
}